Would you be ok only installing the binary version of packages? This would avoid the issues with your compiler. For hexbin, this would mean using the previous release 1.27.3. The most recent release, 1.28.0, was released on Monday (2019-11-11), so the binary package hasn't been created for it yet.
To only install the binary versions of packages, you can run:
options(pkgType = "binary")
install.packages("hexbin")
To keep that setting across sessions, you can add options(pkgType = "binary") to ~/.Rprofile. Please see my other answer for more infromation on the pkgType option.